How would a person with an uninhabitable workplace for credit card equipment go about accepting credit cards?

There are many credit card processing companies that allow you to use telephones to access their processing services. The discount rate for this is usually quite a bit higher than with an electronic transaction. Also, there are some new wireless terminal devices that may work in your environment. You may want to do a quick internet search for credit card processing and/or wireless point of sale terminals - you should get a lot of hits.